The Titanic director continued: "I'm not interested in taking scripts. And that all sounds a little bit restricted, but the point is I think within the Avatar landscape I can say everything I need to say that I think needs to be said, in terms of the state of the world and what I think we need to be doing about it. And doing it in an entertaining way. And anything I can't say in that area, I want to say through documentaries, which I'm continuing."

James - whose next project Deepest Challenge is about deep ocean exploration - teased that the second and third Avatar films could be shot back-to-back. Avatar 2 is expected for release in December 2014.

"We've spent the last year and a half on software development and pipeline development. We haven't gotten to the design stage yet. That'll be next," he added.